In the turbine generator, a stator and a rotor generate heat on the basis of electromagnetic and mechanical factors. As a cooling medium for removing the generated heat, air, hydrogen and the like are used. FIG. 3 shows the entire structure of a turbine generator which uses a cooling medium such as air, hydrogen or the like, and FIG. 4 shows the enlarged view of a cross section in an axial direction and a radial direction near the end portions of a stator and a rotor.
A turbine generator has a stator 1 constituted by a stator iron core 6 and a stator coil 4 wound around the stator iron core 6, and a rotor 5 constituted by a rotor iron core 5 arranged in an inner periphery of the stator 1, a rotor coil 9 inserted to a plurality of slots (not shown) provided in the stator iron core 5, and a holding ring 10 covering an outer periphery of an end portion of a rotor coil 9 protruding to an end portion of the rotor iron core 5, and is structured such that the stator 1 and the rotor 2 are arranged via an air gap 8. Further, a stator iron core pressing member 11 for generally pressing the stator iron core 6 is placed in a stator iron core end portion 7, and the stator is fastened and fixed to a stator frame or the like by using the stator iron core pressing member 11.
Further, as mentioned above, the stator 1 and the rotor 2 generate heat on the basis of electro-magnetic and mechanical factors. However, in order to remove the generated heat and prevent the temperature in the stator 1 and the rotor 2 from becoming excessively high, a blower 3 is provided in the end portion of the rotor 2 or the like, and a cooling medium 14 such as air, hydrogen or the like within the machine is circulated or discharged by using the blower 3. The cooling medium fed from the blower 3 provided in the end portion of the rotor 2 or the like is distributed respectively to a flow path between the stator 1 and the rotor 2, a flow path within the stator 1, a flow path within the rotor 2, and a flow path on a back surface of the stator iron core 6. A flow rate distribution to each of the flow paths is adjusted by partly closing an inlet of the air gap 8 by means of a baffle plate 12 placed in a flow path inlet (an inlet of the air gap 8) between the end portion of the stator 1 and the end portion of the rotor 2, as shown in FIG. 5. The above structure is described in non-patent document 1. In this non-patent document 1, a gap is provided between the baffle plate 12 and the holding 10, and the flow rate to each of the flow paths is distributed by adjusting the gap. Further, the baffle plate structured such that a seal member is sandwiched by two composite rings as shown in FIG. 6 is described in patent document 1, as the same structure.
In this case, in the turbine generator, a leakage flux caused by a field electromotive force and an armature electromotive force complicatedly exists near the stator iron core end portion 7 (refer to patent document 2), and a magnetic flux in an axial direction is incident to an iron core end surface. An eddy current flows through the stator iron core end portion 7 on the basis of the magnetic flux which is incident from the axial direction, and an eddy current loss is generated, so that the stator iron core end portion 7 locally generates heat. In conventional, the heat generation is comparatively small, it is not necessary to control the flow of the cooling medium for removing the heat generation in the baffle plate 12, and the baffle plate 12 is placed for the purpose of distributing the flow rate as mentioned above.
Further, patent document 3 describes a structure in which a plurality of holes 17 are pierced in an entire of the baffle plate placed in the stator iron core pressing member 11 of the stator iron core end portion 7 so as to form a porous baffle plate 16, thereby adjusting a flow rate distribution of the cooling medium in a downstream side of the porous baffle plate 16 within the air gap. FIG. 7 is an enlarged view of a cross section in an axial direction and a radial direction using the porous baffle plate 16. Since an object of this patent document 3 is to uniformize the flow rate distribution within the air gap and adjust the flow rate distribution to the flow path within the stator iron core 6, the cooling medium passing through the holes 17 in a plurality of porous baffle plates 16 is dispersed to an entire of the flow path between the stator iron core end portion 7 and the rotor iron core 5. Accordingly, there is a problem that a flow speed of the cooling medium in the stator iron core end portion 7 is reduced, and a cooling performance of the stator iron core end portion 7 comes short.
In recent years, it has been required to make the turbine generator to have a small size and a large capacity, and there is a tendency that a heat generation density within the machine becomes higher. Accordingly, in order to prevent the temperature of the stator iron core end portion 7 from becoming excessively high, it has been necessary to effectively cool. As mentioned above, a leakage magnetic flux caused by the field electromotive force and the armature electromotive force complicatedly exists near the stator iron core end portion 7, and the magnetic flux in the axial direction is incident to the iron core end surface. The eddy current flows through the stator iron core end portion 7 on the basis of the magnetic flux incident from the axial direction, the eddy current loss is generated, and the local heat generation is caused.
Under the circumstance mentioned above, since the prior art does not take the cooling of the stator iron core end portion 7 into sufficient consideration, there is a problem that the stator iron core end portion 7 and the stator iron core pressing member 11 are insufficiently cooled and are overheated.    Patent document 1 JP-A-6-38411    Patent document 2 JP-A-11-225455    Patent document 3 JP-A-61-161935    Non-patent document 1“Development of the evaluation technique of Rotor cooling method of large turbine generator”, Yoshihiro Taniyama and three others in Toshiba, May 23, 2003, Material RM-03-25 in Rotating Machine Seminar of Japanese Electro-technical Committee.